Purpose: The purpose of this study is to determine whether caveolin-1 is a constituent of photoreceptor synaptic ribbons.
Methods: Immunoblot assay and electron microscopic immunocytochemistry were used to localize caveolin-1 in synaptic ribbons.
Results: Synaptic ribbons were localized close to the active site of presynaptic membranes and surrounded by a halo of synaptic vesicles. Immunosignals of caveolin-1 were clearly detected on the synaptic ribbons in rod and cone photoreceptors. However, the signal was seen neither on synaptic vesicles nor on presynaptic plasma membranes.
Conclusions: Caveolin-1 is a component protein of synaptic ribbons and may be involved in the regulation of transmitter release.